Have dusted the boat off and took it out the other day. This would be the second time the boat has been out since i installed the hcld speakers.

the hcld's make an alternator whine noise when on, and there is almost a bit of a crackle coming through the speaker. i dont get any issues with any of the other amplifiers or speakers which are connected to the same ground.

i dont get any issues with any of the other amplifiers or speakers which are connected to the same ground.

What about the B+ for all the amps, are they all sharing the same battery source?

Quote:

the hcld's make an alternator whine noise when on, and there is almost a bit of a crackle coming through the speaker

Speakers will reproduce the signal they receive, whether its music or unwanted noise. So the whine noise is present when the engine is running and increases in level as the engine RPM increases? The amp's gain level is always a suspect, as well as insuring that ALL audio gear share the same battery source.

Running a ground direct from battery to stereo ground can be a solution but sometimes not a total fix. You can buy rca ground isolator at any car audio place like car toys or best buy that usually fixes the issue. They're like 15 bucks.

Make sure the deck is grounded and powered from the same source as the amps are. Often noise is created when the head unit or equalizer is grounded or powered elsewhere than everything else in the chain. I don't think SMDFSRK means what he said there. Usually an amp needs a big ground, like 4 gauge...your deck likely has an 18 gauge wire to ground. I think he means to do what I said.

To be honest, I read it the same way as Tallredrider. It comes across as if you are suggesting that the amps ground cable be connected to the back of the head-unit as opposed to terminating the head-units ground to the amps ground lug. Although this is not a bad idea, Id still be interested in where the head-units yellow MEM/B+ wire is terminated.

Seems to be like it must be an amp issue with the amp unable to suppress the whine from the alternator.

Well, if the unwanted "noise" is coming in on the signal line, then the amp will do whats its designed to do and reproduce it. So again, is all the audio gear sharing the same B+ source? How where the gains on this amp set?

Sorry neglected this for a while as the amp crapped out. Have another on order but may possibly still have this problem.

Cant test it for another 2 weeks, so will try rewire things correctly based on advice from there.

I have a 0 gauge ground being taken from battery #1 into a 4 way nvs distribution block then 4 gauge to the amps. The head unit is grounded directly to the battery (the ground lug from the headunit sits on top of the one that comes from the distribution block)

Rewire the headunit one so it is going from the distribution block as well? What would you reccomend to pack out the wire so it will sit around in the 4 gauge housing.

Hopefully the new amp will take care of the problem. In the mean time, i'll cover it again. If you have dual battery banks, then ALL the audio gear needs to share the battery positive (B+) source. If they dont, you easily have the potential for the very noise this thread is about.

Technically, the primary ground hub from the battery direct should be at the source unit as stated above because typically all other signal grounds (amplifiers, EQs, etc.) are floating and reference back at the source unit. However, it's just not practical and not necessary. The next best location for the ground hub, including all source electronics, is a distribution block closest to the amplifiers. Same for the B+.

A ground loop isolator in this case is a bandaid and leaves the real problem intact. It can also alter the sound. So don't depend on one unless you have no choice. Fix the true problem. Usually a ground loop isolator is only a necessity if you are mixing components, such as an AC TV and a DC stereo, where the power supplies and audio shield ground references are very different.

Generally an amplifier speaker ground is actually 'above ground' and is common to the RCA input shield ground. If any one of the output transistors are shorted, then this becomes a major conduit for noise, just as if the RCA had no shield, injecting all forms of noise directly into the signal path. Hopefully the problem is within the amplifier and a new amplifier will resolve the issue. If not, then this is usually a very basic issue to resolve by finding and eliminating a supply or ground loop.

Amplifiers have a DC to AC to DC converting power supply that serves to step up the voltage. Inherently it's the best possible noise filter available. So there is no form of DC input filtering required on an amplifier.

Mike and I are saying the same thing. We both understand the issue the same way. I'm being a bit thorough. Sorry, I tend to do that. It's this simple.
Ground the HU to the same distribution block used by the amplifiers.
Power the HU to the same distribution block used by the amplifiers.
Both distribution blocks are naturally close to the battery in most cases.
That's it.
Here is the reason why I'm making this distinction. The most important link for having a zero voltage potential difference is the signal path combining the audio equipment.
In some cases the amplifiers may be a long distance from the battery. In that case, it is extremely important that the HU B+ and ground reference point are close to the amplifiers and not the battery in order to keep the resistance in this critical path to a minimum. A resistance differential results in a voltage differential which results in a supply or ground loop which is a perfect conduit for noise to travel.